In the last years mobile communication became more and more popular. New developments in this field of telecommunication open up an ever increasing number of new application areas.
One of these new application areas is a M2M application. M2M stands for machine-to-machine, mobile-to-machine and/or machine-to-mobile communication. The purpose is to enable controlling procedures, monitoring procedures, parameter setting procedures, transaction procedures and the like with machines such as vending machines, elevators, pumps and meters and the like via a mobile communication system. In other words, communication connections between systems, devices and individuals are to be established. This can be done, for example, via the Internet with which mobile communication networks can already establish connections and perform data transmission. As wireless access methods can be used, for example, CSD (Circuit Switched Data), HSCSD (High Speed Circuit Switched Data), GPRS (General Packet Radio Service), USSD (Unstructured Supplementary Services Data) and SMS (Short Message Service), which are all commonly known to a person skilled in the art and for which a detailed description is omitted. M2M applications can be employed in different types of carrier devices which are placed on mobile or static platforms, for example static vending machines or mobile devices in cars, or the like.
When a wireless connection for a communication unit of the M2M application is used, as for example a mobile communication connection, the M2M communication unit is treated like any other common mobile station (mobile phone). This means that all procedures to be executed in order to establish a connection between the M2M communication unit and the mobile communication network are done as usual, such as call control, mobility management (abbreviated hereinafter as MM), and the like.
Commonly agreed standards for MM, e.g. in a GPRS environment, are disclosed, for example in 3GPP (3rd Generation Partnership Project) specifications TS 24.008 V3.9.0 (2001-09) and TS 23.060 V3.9.0 (2001-10). In these specifications, among others, in particular MM processing and the adjustments of MM timers (ready timer, periodic routing area (RA) update timer, mobile reachable timer) in mobile stations and network control nodes such as SGSN (serving GPRS support node) are described as they are usually to be performed. The terms standby state, ready state, ready timer, periodic location area update, periodic RA update, location area (LA) update, periodic RA update timer, cell update, mobile reachable timer, which are commonly known by a person skilled in the art, are for example defined in these referred 3GPP specifications TS 24.008 V3.9.0 (2001-09) and TS 23.060 V3.9.0 (2001-10). A particular example of MM procedure is how long is an mobile station maintained in ready mode (2G GPRS) and how often a periodic update (e.g. periodic Routing Area (RA) update in GPRS) is performed.
Currently MM timers are optimized based on average behavior of a Mobile station (MS), i.e. MS mobility (affecting e.g. number of RA update; number of cell updates; probability to move out of coverage) and MS traffic pattern (affecting e.g. probability to be paged). In addition, MM timers takes into account various other factors such as a RA size (affecting e.g. number of RA update and paging load) and quality of coverage (affecting e.g. probability to move out of coverage).
For better understanding, a short description of present mobility management in different mobile communication systems, e.g. in a mobile switching center (MSC), second generation serving GPRS support node (2G SGSN), 3G SGSN, and relevant differences thereof is given. These, however, are known to persons skilled in the art.
A 2G SGSN tracks the location of an MS at a cell level in ready mode, and in RA level in stand-by mode. The MS and network stay in ready mode for the duration of the ready timer after the last uplink transmission. After that both change to stand-by mode where RA Update are made when RA change or periodic RA Update timer expires. In order to prevent fast moving MS to, stay always in ready mode (as they always make cell update before ready timer expiry), the SGSN may force the MS to move to stand-by after a routing area update procedure. The ready timer and periodic RAU timer values are indicated to the MS in the attach accept or RA Update accept message.
A 3G SGSN tracks the location of an MS at radio network controller (RNC) level in MM-Connected mode, and in RA level in MM-IDLE mode. RNC tracks the user at cell or URA (UTRAN (UMTS Terrestrial Radio Access Network) Registration Area) level. The RNC has a mobility management (sometimes referred as location management) mechanism very similar to the MM mechanism described above as it also has periodic cell or URA update procedure. The periodic timer (value) applicable is broadcasted in the area. The MS and network stay in MM-Connected mode until this one is explicitly released. A corresponding release request may be initiated from the RNC (e.g. triggered by an inactivity timer or triggered by detecting the maximum number of URA update without data transmission) or from the SGSN (e.g. by moving back the MS to MM-Idle state after completion of a RA update procedure). In the MM-Idle mode, RA updates are made when the RA changes or when the periodic RA update timer expires.
The ready timer and periodic RA update timer values are indicated to the MS in the attach accept or RA update accept message for both 2G and 3G. It is to be noted that this ready timer value is sent also in 3G protocols (due to the desired interoperability with 2G) although 3G does not comprise a ready state.
An MSC (2G or 3G) tracks the location of an MS at RNC or base station controller (BSC) level in MM-Connected mode (i.e. during a call), and in LA level in MM-IDLE mode. The MS and network stay in MM-Connected mode until this one is explicitly released. The release request may be initiated from the RNC (e.g. due to a loss of coverage during the call) or from the MSC (e.g. due to an end of the call). In MM-Idle mode, location updates are made when the LA changes or a periodic Location Update timer expires. The periodic Location Update timer value is currently indicated to the MS in the broadcast information (thus, all MS in same location area use the same value).
However, when a large number of additional communication units for M2M applications are introduced in the existing mobile communication network structures this will result in an increase in the signaling load for the networks.
In document WO 00 38469 A an apparatus and a method for providing page messages to mobile radios based on the mobility rates of the mobile radio are described. For mobile radios that are relatively stationary, page messages are sent to a cell in which the mobile radio resides, while radios which are increasingly mobile receive their page messages on a local area basis. The mobile radio only performs location updates when the situation is optimized for doing so depending upon the mobility of the radio, the introduction of a new cell, the introduction of a new location area, the expiration of a pre-determined time limit and the status of a new cell location flag. A function is defined for location updating on either a locationary basis or a cell basis in accordance with each of the above factors in order to optimize the burden of location area updating and unwanted page broadcasting.
In document WO 99 52306 A a method in the packet switched data transmission between a wireless communication device and a packet network is described, in which data transmission between the wireless communication device and the packet network is controlled with at least one packet switching controller (SGSN). A group of connection states is defined in the method, from said connection states one is selected at a given time, and the selected connection state is set to the wireless communication device and to the packet switching controller. In addition, said connection states are defined in the method to be: a ready state, in which packets are transmissable in an activated data transmission connection, a standby state, in which data transmission connection packets to be transmitted and received are waited for, and an idle state, in which the data transmission connection is deactivated. As a connection state also an extended ready state is defined, to which a transition from the ready state is conducted, and in which data transmission connection packets to be transmitted or received are waited for.
In “Location management strategies for mobile cellular networks of 3rd generation” by D. Plassmann, Vehicular Techn. Conf., 1994, IEEE 44th Stockholm, Sweden, 8.10 June 1994, New York, N.Y., USA, IEEE, 8 Jun. 1994, pages 649–653, XP010123353 ISBN: 0-7803-1927-3, several location management strategies applicable in cellular networks are described. Analytical modelling approaches for signalling cost minimisation are discussed. Results of a GSM based case study are given which are applicable to cellular radio systems of the 3rd generation like MBS and UMTS. A hybrid dynamic strategy is proposed for a public MBS.